FrostList

When to Winterize Your RV in St. Louis, MO

ON TRACK127 days until first 28°F freezeNov 15

St. Louis's deadline to winterize your RV is November 5: the local first 28°F freeze runs November 15 on average and November 2 at its earliest (1991–2020 normals). The early-odds date runs roughly 13 days ahead of the median, so build in that buffer.

OUTLOOK

Typical first first 28°F freeze near Nov 15; local deadline about Nov 5. The live 10-day outlook loads here.

Local freeze dates for St. Louis

ThresholdEarly (1-in-10)MedianLate (9-in-10)
32°F (light freeze)Oct 24Nov 4Nov 21
28°F (hard freeze)Nov 2Nov 15Dec 4
24°F (severe)Nov 9Nov 26Dec 15

NOAA station: St Louis Sci Ctr · 3.9 mi away · 515 ft elevation.

For St. Louis, the nearest NOAA station with freeze data is St Louis Sci Ctr, 3.9 miles out at 515 feet. Median first-freeze dates there run 32°F by Nov 4, 28°F by Nov 15, 24°F by Nov 26. Year to year the 28°F date has ranged from Nov 2 to Dec 4 — about 32 days apart. Spring's last 32°F freeze clears around Apr 1. Snowfall averages 14 inches a year, first reaching an inch near December.

In St. Louis, freezing nights (32°F) typically begin around Nov 4 and the first hard freeze (28°F) follows near Nov 15. The 32°F date swings from Oct 24 at its earliest to Nov 21 at its latest, near 28 days. The last spring freeze averages Apr 1 and as late as Apr 18, which sets the safe window for reopening outdoor water and de-winterizing gear. At about 14 inches of snow a year, the freeze — not snow load — is the thing to plan around.

Your rv checklist

  1. Drain the fresh, gray, and black tanks, then drain the water heater only after it has cooled and lost pressure.
  2. Bypass the water heater so you do not waste six gallons of antifreeze filling the tank.
  3. Blow out the lines with a compressor at about 30–40 psi, then pump non-toxic RV antifreeze through every faucet until it runs pink.
    Helpful gear: RV antifreeze (6-pack) — Recommended pick
  4. Use a water-pump converter kit to draw antifreeze straight from the jug through the plumbing.
    Helpful gear: Water pump converter kit — Recommended pick
  5. Pour a cup of antifreeze into each drain trap and the toilet to protect the seals.
  6. Fit a blow-out plug at the city-water inlet so you can clear that line too.
    Helpful gear: Blow-out plug — Recommended pick
  7. Remove batteries or put them on a maintainer, and store them off a cold concrete floor.
  8. Cover roof vents, close the propane, and set out traps or deterrents so mice do not move in.

What to have on hand

RV antifreeze (6-pack)
Non-toxic pink fluid for the fresh-water plumbing and traps.
Recommended pick
Water pump converter kit
Siphon kit that draws antifreeze straight through the pump.
Recommended pick
Blow-out plug
Adapter that lets a compressor clear the lines before antifreeze.
Recommended pick
Heated fresh-water hose
For anyone staying hooked up through a cold snap.
Recommended pick

What this means locally

St. Louis freezes close to Florissant (Nov 13) and later than Belleville (Oct 30) — a reminder that even nearby towns differ by days. Statewide, Missouri prep dates run Oct 16 through Nov 5, which is why St. Louis gets its own number rather than a Missouri-wide average. The same freeze also decides when to shut down your sprinklers and winterize a boat.

Other winter jobs in St. Louis

Every task below is dated to St. Louis's own freeze and snow normals.

Sprinklers → Nov 5Frozen pipes → Oct 24Ice dams → Nov 15Car battery → Nov 15Snow blower → Nov 24Sump pump → Apr 1Boat → Nov 8Motorcycle → Nov 4

See the full St. Louis winter checklist, in order →

Frequently asked questions

At what temperature do RV pipes freeze?
An RV's exposed plumbing and thin-walled tanks can begin to freeze once temperatures sit in the mid-20s for a few hours, sooner than a house because there is little insulation around the lines. That is why the winterizing deadline tracks the first 28°F freeze rather than the first light frost.
How much RV antifreeze do I need?
Most travel trailers and motorhomes take about two to three gallons of non-toxic RV antifreeze, and larger rigs more. Bypassing the water heater saves roughly six gallons you would otherwise waste filling the tank. Buy an extra jug; stores sell out once the first freeze warnings hit.
Can I just use my RV furnace instead of winterizing?
Relying on the furnace is risky. A propane run-out, a tripped breaker, or a dead battery during a cold night leaves the plumbing unprotected, and the furnace may not keep the underbelly and bays warm enough anyway. Draining and adding antifreeze is the dependable way to protect the system.
How do I winterize an RV water heater?
Let the tank cool and lose pressure, then drain it and, if fitted, pull the anode rod. Do not add antifreeze to the water heater tank; instead, set the bypass valves so antifreeze skips the tank and fills only the lines. Fresh antifreeze in an unbypassed heater just wastes several gallons.
When is it safe to de-winterize an RV in St. Louis?
Wait until the last spring freeze has passed, which averages near Apr 1 here. De-winterize by flushing the antifreeze from the lines, sanitizing the fresh tank, and checking for leaks before a trip. Reopening too early risks a surprise late freeze on a charged system.
Do I need to winterize an RV stored indoors?
A reliably heated indoor space that stays above freezing protects the plumbing, so full winterizing may not be needed. But an unheated garage or barn can still drop below freezing on a cold night. If you cannot guarantee the space stays warm, winterize to be safe.

Data: NOAA 1991–2020 normals via St Louis Sci Ctr, live outlook by Open-Meteo. Sources · Methodology. Last updated: July 11, 2026.